High tension cut-out and the like



Aug. 9, 1932.

E. NT NORDHEM HIGH TENSION CUT-OUT AND THE LIKE Filed June 6, 1930 die@ i i* 'JU-VPE i Patented `9, 1932` 1,871,194 f V N ERIC OBIDHEM, F CHICAGO, ILLINOIS nien TnNsIoN cinc-our` AND 'rnnfrfrxn Applicationled .Tune 6, 1930.` Serial No. 459,601.

l This invention relates to certain improve-i` ments inlcutLouts especially intended for o1; enin high `tension circuits and the like. l While the .construction herein disclosed is i l 5. especially intended for controlling high tension circuits and thelilie,` still it Will be un` derstood `that structures embodying the features of the present invention may also be l l used for theopening of other circuits. There- `1 fore I do not intendto limit myself to the use Vof said features in connection with high tension circuits,\although it will be understood that the design and construction are u. especially intended fforthis class of Work.

One `of the features of the invention relates to the provision ofzan `arrangement in lwhich `the physical operation of opening the circuit c is performed `byfpovver` `derived from `a suit able compressed gas.` Thiscompressed gas may, for example, by compressed air, or carbon dioxide or `nitrogen under compression, er any other suitable gas7 preferably an inert i gas ofpovverful arc extinguishing proper- ,.,Lties t t f `One object of the invention is toprovide afconstruction in whicliuse is Vmadeof a self-contained .container for the compressed gas, Which containergconstitutes a self-cony. .i tained unit `and canfreadilybeset intoplace` or removed fromthe remaining portions of thel structure ofthe high tension `cut-out. Thisself-contained unit may be readily `set y into place or removed from the remainingportions of the structureythus making it possible to substitute a new container which has" been charged with the appropriate gas under the,desiredpressure at somelilling or charging station. y y l Another feature of the invention `relates- G' to the provision of an arrangement such that i thereleasing ofthe gas Will be accomplished` i at the proper time very suddenly and through]` i s s i initial operating force in combination `with a a relatively large opening so that a very` pow- Vg erful force may begenerated for operating the circuitopening device. At the same `time the arrangement Vis such that the-:device Will be sensitive tol the degree necessary to insure accurate operation and atjthe same time to y 0 avoid premature improper functioning of;`

the gas y release.

member Whose movement serves directly-and A further object in this connectionfis to provide an `arrangement such H that the gas will normally b e sealed into the container in a perfectly gas-tightmanner so that there Will be substantially no leakage or Wastage 5s of pressure therefrom. Consequently, the charged unit `Will maintain and retain its pressure for a long interval oftime. This? Will also insurea definite certainty of oper` ation at the critical time even when the de-` l vice has been standing fora long intervalA Without attention.` y n y l n Another feature of the `invention relates" to the provision of an improved construction` definitely toopen the circuit. This movable contact member normally makes connection with stationary contacts under;considerable pressure which entails the existenceof a `oe`rtain degree of friction Which must be overcome at the instant the movement of the con-` tact member commences. One ofthe objects of the invention is `to providean arrange-U ment such that the gaspressure of the re` leased gas is directed `primarily Aagainst a piston of relativelylarge sizeso that a large operating force isgenerated at the com mencement ofthe "circuit opening operation.`

The movement of this piston of large` area continues through a sufficient distance `to`in` 801 sure a `satisfactory disengagement of `the` friction parts. Another feature of the invention relates to the provision of another piston of smaller size in` conjunction therewith so that the continued movement ofthe movable contact member for the purpose of"complet` ing the circuit opening operation through a considerable distance of traveldoes` not en-vA tail the consumption of more than a relatively smalladditional amount of operating gas. 'By the foregoing combination ofparts, I

am enabled to generate the necessary large` Y greatly reduced total gas consumption forthe production i. of the total desired amountof movement of the movable contactmember." f `Another feature of the invention relates*` s l s @recinti the device S0 that a is possibieffr 100 y quenching Iability of the,` bathV is'fthus im`-` 25 a ,device a person to ascertain immediately by examination of such` indicator as to whether or no p i 7 whereit setsinto thecap 8;

A collar `member 12 has a downwardly dethe device has functioned.

Another feature of the inventionrelates to the `provision of an improved means of ,retaining the movable contactl member inthe raised orcilrcuit `opened positi`on,= and for, establishing' connection therewith circuit opening operation.

In connect' on Vwith the eXtinguishme-ntof.

place Vthe'fbath under pressure -greaterthan in ,size withv consequent increase otfthickness othe oil layers between vthe bubbles.V The proved; and thearc- `will killed or extinguished. h .y

Another feature relatesl to the provision of f which canbegvery easily resetfor another operation.

more quickly inafterdescribed and-claimed. i j

i mf

. 1Inthei drawing:

Figure l` Shows broken away in Order@ `shorten up the fleure'- 4 Figure Y 2 `showsj- 4a ffraginentary section Figure 2 may alsobe consideredlas a sec l 1 thedretionfo the arrows s` {,f

Figure shows `.a top plan 'viewpofthe de.- Y

` The. upper end of the vice of, sigaren mi 2; r f Figure `4l shows anv oifset z rection ofjtheiarrows, thefrighthand portion of the figure being Figure. 5` shows a cros showing electrical 4connections o-,the'deg` vice.A

ff The arrangement iillustratedI includes tu-` cylindrical bodymember 7 of glass or.othersuitable'insulating material. Agcap l fr Shavinglaiiange `9, is provided'forthelowerend of the member?, said lower end `being setlwdowlnlintothe `flange 9 .and sealed into. .iplaceby` leader theili-ke lOvin, customary during the. U Y f kinto place between the end `oiithe tubular member rZand the shoulder 16 of the collar 12.

A" nipple '17.is" threaded into the upper end Y the arc by a quenching bath',"`it" is notedlthat ,1f y Y `ofthe collar 12 andprojects beyond the same f as the terminals are pulled apart to open thev circuit, there form gas bubbles which,A are separated by layers orV `ilmsoi Lthe liquid.

Thev gas of these bubbles is ionized and they-j are gthereiore., of LconductingY quality. The quenehingactionpof the bath is due to the, Y layers or filmsfof liquid between thebubbles.

One feature offthe present. invention is `to w Other objects v11161uses of" the iiwention` will.. appear trom a detailedgdescription ofA i the same.which consists, in theivfeatures of'v constructionand combinations of parts here.

h a longitudinal section through a device :embodying the `i'eiatures -ot the present invention, portions thereof being ing of the plug 21.

throught-the upper por-tionvoflthe; `device tak` anu-angle of 4554 to thersecti'on otFigure i steppeddow'n tothe visual., indicationzdevice; f

manner. vPreferably, also,`a washer or gasket 11 is placed `at the lower end of the member pendinglangel which receivesthe upper end .ofthe tubular member 7, whichV is sealed in., place `by means of Vlead l `orthev like.

Preferably, also,a gasketfor washer 15 isset? a sufcient `distance to', enable ythe charged compressed gas unit to be screwedinto place.

A block -A18 is set into the collar 12 and de- "pende,` downwardlyV into the chamber 17'; and

a shoulderV 19 preferably formed inthe Vcolular k12 soA as to receive aslight enlargement oi the member 18 and thus-prevent said mem-'y `her from dropping down. Y

"5 The lower.portionof` themember 18 islproe vided with a pocketlor chamber 2O of `rela'- tively rlarge, sizeq The I lower 'endl thereof is closedfby a plug 21,"but'the`re isa series of vlower portionlof thev member 18 and com- `openings `2,2 reaching laterally-throughthe p municating with the. lower end of the cham-` Y f berf20f.V For this purpose the plug 21 is`pre'- erably provided with an encirclingV groove 23'` which communicates with theopenings 22V and allow a very rapidtransterot gas intoV the chamber 20.

The movable contact rod `25 extends down through a central opening-260i the piston A large;plungerx2lvr isfloc'ated and lwerksf."VV e withinthe chamberQO abovethe position of 24 and through a companioncentral open` l rl-herev is astationary Contact member the circuitis closed. i

vIIlO'vablecontact rodi carriesjahead .blocklf Themember `18 is.

Vprovided, with ajcentral bore32 ofproper size to receive'the headblock 31 as the-mov.-

able Vc'zontactrod' 25 travels upwards, the head a Y block 31travellingthrough the bore 32with i h i h sisectionlon 'the line 5.5 of-Figure 1,".lookingin3vthe,directionofg ablooseit.` "A plug' is screwed'into the upper'end of the member 18-so asto closeV th\e`bore"32;,and preferably a block Bilgof leather, feltfor otherrsuitable material for' cushioning isplaced on the lower endof the plug 33'so"fas.to receive the-impactot thev headjb'locklas the rod 25 reaches the up'- per endet" itstravel.

lThemember 18is'provided above the position of thecylinder lopening 2O,l with an opening 3450i? somewhat reducedlsize. Ain'enfb` ber 36 isIV setinto said opening 35 withatight Ltit and/,has a series ofupwardlyvextending f i opening26`of `.the piston 24. i

`cylindrical member 7.

. `contact ingers37 which'normallymake con` tact with the fhead block 31"whe`n the circuit 31 travels away `from 31. n Thelower face of saidpiston block 38 A1s preferably bevelled'andh makesla `nice fit against the upper portion of theV central The member 18 is of somewhat smallerexternal diameterthan the internal size of the Normally the` device is filled with a suitable quenching liquid up to@ substantially the level 39 which is slightlyl i the portion 43 with sufficient `below the `lower end of the member 18. Preferably also, a `block 4() is secured to the bottom face of the block2l,` said block 4() havinga longitudinal slotted opening 41 which s leaves i onfone side a relatively long spring member 42. 3` Theblock 40 is `provided with a seat 43 directly opposite tothe center ofthe spring member 42; andthe movable contact rod `25 is graspedbetween thespring portion 42 and i vent the `contact zrodffromdropping down `while atthe lSametime not interfering with its i upward movement when projected upwards by the circuitkopening operation.`

n n. i. When the device"` `is to.; be operated, com- This compressed pressed gasA `is suddenly delivered down throughk the annularjspace `44 between the member 181and lthe cylindrical member 7.

'gas flows through the openings 22 andl23 and against the bottomfaces of the pistons 241and 38. Of course the com-` pressed gas also reacts against the surface of theliquid 39but *the samezis suliiciently held by the strength ofthemember 7. i 1 `The compressed gas thus exerts a powerful `upward force against theflarge piston 24 whose area supplements that ofthe smaller piston 38. `.The vertical dimension of the cylindrical chamber is `sullicient to allow for thewnecessary upward movement of the rod 25 to disengage from` the contacts 30 and i 37. Then the movement ofthe piston `24 is` arrested. The smaller piston 38 then "enters through the memberf36 andat thesame time i the head block 31 enters the `bore 32 and travelsupwardtherein. The resultis that the `gas pressurefromthat time forwardis eX- erted on the relatively small area of the pis'- ton 31 The area thereof 1s suclent to Insure l merous perforations y 64 through which `the the desired `amount of upward force `to continue upwardtravel ofthe contactirod 25 until arrested by thepad 34; andy due tothis relatively small sitze the amount of gas `consumption necessary for this `portion of the operation isrelativelysmallQ` n `The compressed gas for bringingahout the A foregoing operation may be derived from any y Inthe presentarrangement I have "provided aV flask "orcontainer therefor suitable source.

n theupper end of the nipple terminates in'ahorizontalllange 46 from friction to pre" whichwis removably attached to `the `upper portion lof the structure. p y sleeveor collar 45 which can be threaded onto which there isa tubular section 47 reaching upwardlyabovethe flange 46. Ablock 48 is secured into the upper end of the tubular sec#` tion 47,1said block having a downwardly eXf tending bore49wliich rea-ches "partly through the block. i Oppositetothis bore 49` the block 48is externally lgrooved as shown at 50 so as -to provide a very thin wall at that point.

Conseopuently,l by forcing the lower end 51 of the block sidewise,:it can be easily broken off at the position ofthe groove 50. Astem 52 `is threadedinto thelower portion 51,` said. stem reaching down through `the tubular section47 to the lower end thereof.

A cap shell 53 is set over the tubular section 47, thelower endof said cap shell reaching down aroundthe collar 45 to which it is secured in gastight fashion. p The space between the cap shell 53 and the tubular section 47 constitutes a chamber for the reception of compressed gas. This chamber can be easily charged in any convenient manner. In theconstruction illustrated, there is provided acheclrvalve 55 which is normally set by a spring 56. After the compressed gas has been delivered into the chamber, the checkvalve will retain ittherein, but a screw 57 may then be screwed into the lower portion of the member` 54 and secured by soldering or otherwise. y 1

Reaching downwardly within the tubular section 47 there is a spring arm 58. The u per endthereof is rigidly secured to the tubu-` lar section 47. `The lower end of this spring arm 58 `is normally retained under tension by a tension wire 59, one end of which extends through a slot 60 in the lower` end of the arm 58. The other end of said tension wire is connected into a plug 61 which passes through an insulating sleeve `62 in the wall of the i When a current of sufficient inmember 45. tensity flows through the `wire `59, said wire burns ofi, thereby releasing the spring arm 58. Said spring arm then exerts a suiiicientlateral pressure on tothe pin 52 to suddenly `deflect the same to oneside and thus `break olf the lower portion 51 `of the member 48.

This `includes "a .i i

This collar i Preferably a, plate63 is set into the collar i 45 before the member 45 is screwed on to the same, said plate 63 .being provided with nugas is allowed `to flow down when the device is released;

The gas flowing `down through the .open-` 17 continueson .i i. down through passages 65 to the upper end" dropping downintothe lower portion of the device when it functions. A j y 1 z purpose of` pre- 6611s of rectangular form, its innerwsurface being insulated by va paper layer orfV the ililre V13,4, butfthe're` :is Vani inwardly reaching zinsulf ating collar 67 `at the lower end of` said hood,- l which collar 67y "liasaa V'circulargcentral .open-J Y i f ingto receive-.the chamber153-..; :Theupper V portionoi:l the hood 66 is inturnedf'asshown at 68'a`1id vis .provided with: a centrall circu- L` larope ing which1receivesageircular block' of insulating fmaterial69. The `top `face! 'of this block of. insulating material 69 `carries a semi-circular'plate 70; The? upper portion 68ofthe hood 66 is inturned as shown inFig-fV uref 41 `and terminates in` a1 member 71 oppi i site tothe centralv portion of the member V70. The fuse Z2 normallyconnectsthe cen-z tral portion of the member 7 Otolthe block 771V so that the "current normally flows kfrom the hood y across the` member 71, acrossythe fuse to `themenfiber. 70. Thejendsof` the member 70 connect Vby 'screws' 81' and-82V into: f

blocks 83 in the roof `ofthe-'shell 53. Con-` sequently, the fcurrent flows from the-#menn-u berV 70,' down through the screws 81 {intothe shell 53 'and fthusiin'to the member 45, nipple 17, and collar 12;,'1`hecurrent then flows down through the blockf18, con-"Y in place. Tlieplate 7 3 has an upwardly exs4 .tending stud 7 5 whichireaches up through" theinsulating block 69"'to` a positiondirect! ly beneath the `iuse 7 2, with *which however,

Vitidoes notnormally make Contact there"be` ingpreferably a layer of paper betweenthese' parts. `{Vl/men theY fuse 72l blows, thearc so created, and the high tensionf current, jump froinjthe end of the u`se`72or `thestud 71, tothe stud .7 5 and thencedownthroughtthe plate `73jand springftinger 17,4; through theI tension w1r`e159, spring hgnger" 58, `tubular section e?, and member', etefThis causes y the full overload "current tobey suddenly p i groovet() tot i lt will :be understood that the compresseddiverted"into thetension wire 59 which `thus burns oif andV relieves thespiringlinger 58.j

This' immediatelycauses a large lateralpressureagainst the Aiinger` 52 a-ndbreaks" off,`

the bloclrportion` 51 atthe positionof the release thefgas as already exe, plainedw'* gas container y' can be readily y reifnovedl` and Y a new Vunit set into place by merely unscrevw` lthe gfcollar" L15 Cfrom `the upper end" ofthe are 1?- Wenas alare;

which can" he set'downrover the :chamberf53 Thisehood y 'of mica or paper, pr P in place by a flange' 80.5 Theriu'pwardtravel' screwed froriiftthe inipple 17 thegrid-plateesiGomesbewaart-eicouarfiagheplages Y may: berfunscrewed a frodi or others` tool may; be introduced` for the purpose-` .et push,` ing the movable:Contact` rod 25 downwardly toresetith'e same@ 1; f i 1" :In order to give 1 :a lvisual-V indication of the condition of 'the device, Iihave" provided ia laterallyil extendingr gas: passage 76, reaches frm'fthe upper Aportion otthe bore 32 to a groove 7T forinedaroundvtheupper portion oftherbloclr 18 above the posi-tionfoi cates with an oudtvvardly` extendingpassage` 78 `in the member imi-which passage.78.` is

'ferably colored, Vheld eo Vnormally closed'ebyla relativelythin wall 79*` 31 willf drive fairll'yor @gas ahead: of:` the samel a i y andl out `through:ithepassages:76 andf78, y

ing `the desiredvisual"indication.m

thereby Aburstingthe diaphragm 7 9 and giv Iwishto pointfout that-by the use of comif pressed gas `forjinsurng thef=move1nent of the movable contact "member, aml Aable to secure a much( more rapid "and instantaneous action than *cani be obtained" by `theV inse-lot'l va; spring. 5gg-,This iis'beca'u'se theY spring when' released must' rst:` overcome the' inertia off those' portions; of? it. which `undergo movement, being the entire' massi oit-the. spring` except: the very end; portion," which, isffas-` tened stati oii'aryfiL 1 The f net inertia `of `the spring can-be mathematically `calculated tali;

rates. On fthe contrary, `=vvhereicompressed.. gas is used, l Vthe only finertia of "substantial amount to be overcome. is the inertiaofl the piston which is the*l element sou Vlng intouraccount thefact that Lthefdi-erent portions? of .it'iare accelerated zat" different moved. -'lhe inertia .of thel gas itsebliis" rela-V tivelyinsignicantr 1 i y 1, l A1While I, have 'herein shown and described, only a singlefembodimento the `features of my present invention,lfstil ll :do not intendfto' iior f limit. myself thereto-except as TI *Amay do; so

intheclaims; .i ,1 Y y s 1t willbe noted" that upon operation of this device the quenching liquid If is subj e'cted `to` al hydrostatic` pressure greater. than atmospherie loyan amount equal to v.the e gas pres-.1

sure ,which is exerted against `the `pistons 24:"

and 38.* ,This is also equal tothe pressure off quenching liquid,

theV gas i pressing down on ythe surface oflthel Owing tothe `above system, 3 t

liquid uitselfgV is i subjected to v a considerable l increase of; hydrostatic pressure; at Athe very` time that-the are lsbceingextinguished namely, at the time thefrod 25; separates rOfllf-the Contact fingers This resultsginsubstair tial reduction gof the volume `andy size oi'\ rthe`` gastaba@ swhaaeihickness of imams 011 layers' YAYQi :Isuenchngf liquid@ ,between the:

it i i i vertically movable contactrod having `its "da` .i .i

y sages aforesaid, substantially `as described.

y sulatingimateriaha closure for thelower end y thereof, astationary contactat said ,lower ""1"0 bubbles is correspondingly increased.` For `these reasonsa very much imore `perfect and quicker acting extinguishing operation" is `produced than would otherwise be the case.

Iclaim: "l l n 1.`In-adevice of the class described, the combination of acylindrical chamber of inend, a ferrule secured to the upper end of said chamber, a downwardly extending mem- "bersecuredto said ferrule and having a cen-` tral longitudinally l extending `cylindrical bore of small size terminating atsits lower end 1n a cylindrical bore of enlargedisize, a

lower endworking in conjunctionvwiththe stationary contactaforesaid, and having on itsupper portion a piston enlargement adapted `to travel withinthe cylindrical bore of small size, `an enlarged fpiston surrounding saidcontact rod and of proper size totravel r-within the cylindrical bore of enlargeldksize `in sealing fashion, said enlarged `piston `bearing against and liftingaga-instthe piston of i smaller size aforesaicha vent opening coml i municatingwith theupperend of the cylindrical bore, a `,diaphragm sealing fthehouter endof said ventopening and subject to rup" ture when the i piston rises through the y bore `of smallersize todthereby give a visual `indication, quenching liquid within the cylindricalchainber below the pistons, there being suitable passages "for `igas in kthe. upperpor-i `tion of the devicelcommunicating withfthe space beneath: the pistons and above the contained liquid, together with a removable ,sealed containerfor compressed gasremov-v `:ably connected tothe upperportion ofthe device and in communication with the pas` 2.In a device `ofthe clas'sdescribed, the

combination lof a cylindrical chamber of insulating material, `a closure for the lower end thereof, a :stationary contact at said lower end, a `ferrule secured to theupper `end of said chambenadownwardly extending member secured `to said ferrnle and having afcen- Ltral :longitudinally extending cylindrical ``g`bore ioflsmall size terminating atitslower l end init a cylindrical boreof enlargedisize,

ga vertically movable :contact y rod having i its lower s end working in conjunction withthe )stationary contactlaforesaidyand having on its upper portiona piston enlargement adaptl ed toltravelwithin the cylindrical bore of Vsmall size,` an enlarged piston surrounding i :said Contact rod land of: proper size to travel within the` cylindrical bore of enlarged size Ain sealingffashion, said enlarged `piston bearfing: against and lifting against" the piston of smaller size aforesaid, quenching" liquid withl lin the cylindrical `chamber below the pistons, *there `being `suitable i passages `for i gas the i upper `portion of the device commnnicating lwithgthespace beneathltheu pistonsand fabolve the contained liquid, together with a removable sealed container for; compressed gas ire,- movably connected to the: upperportioniof the l device zand in i communication with the passages aforesaid, substantially asidescribed.

\ v3. `In a fdevice of theclassidescribed, the" combination of a l cylindrical chambeni of f ini sulating material, a `closure forthe lower end thereof, `a stationary i contact at `said lower end, a ferrule secured `to` theupperijendaof said chamber,a downwardly extending member secured to said ferrule `and having sa cen tral longitudinally extending ucylindricaljbore ofsmallsize terminating at its lowerendiin a cylindrical bore of enlarged size,avertically movable 'contact rod having its vlowerfxend working in conjunction iwithfthestationary n contact aforesaid, and having on aitsaupper portion piston `enlargement adapted ,-.to travel `within the` cylindricali` borewofismall size, an enlarged pistonsurrounding Saidcon` tact rod and ofiproper` size towtravel` within the` cylindricalbore of (enlarged rsize in seal# ing fashion, said enlarged `piston bearing "against and lifting against',thewpistoniof smaller size aforesaid, there being suitable passagesfor gas i-n itheuppertvportion fathe y devicecommunicatingiwith;thespacelbeneath `enlarged size, means `for arresting `movement ofthe large size piston priorfto"l arrest "of 1 movement ofthe piston of smalljsize, together y `withimeans for introducingngasiunder pres,-

-surebeneath the `piston of enlarged sizerffbr p l the `purpose of commencinga ,circuit opening operation, the movements .of therodi. and piston of small' size` continuing: into ,theibore of small size afterarrlestof movement 'ofthe piston of enlarged size, substantially asldescribed.; i

` l 5;.1In a .device lof ther-classidescribed,

combination of `a stationary Contact, a movz- `able contact l rod-jworlnng in :conjunction therewith, the rod breaking connectionlfrom the stationary contact after a limitedamount -of movement, a stationary cylinder having .La

lbore of small size terminating at its 'lower endin a Eboreof enlarged f sizeand length A substantially as" great as "the "amonnt of rod movement ifor such disengagement; a pistn V an ' roiifsmall size-on -therodzadaptedtowvorl sizesurrounding` the! rod and located bei thebore ot small size, apiston 4oienlarged neath the pistony ofV small size and Working in the bore ofenlarged; size, meansior arrestf ing movement of the plston of largesizeprior to. arrest'of movementof .the piston of small andipistonvof small size continuing into the A v bore ofgsmall size after arrest of movement 'of the-piston:ofeniargea Seize, substantially Vas, described-f "1- l i Y' e ablejcontactmemberWorking in conjunction therewith,f they arrangement being suchfthat Y et the lpartsare in engagement through a' limitf edzdistancegof travel, togetheryvvith means for the othercylinder 'and piston, meansfor 1ar- `resting movementothe piston 'of large.k size prior to ,arrest of movement-ofthe piston of small size, means vfor initially a. introducing A gasunder pressure intoengagement vvithV b oth K of "said pistons to commencevthe" operation,

n and `for thereafter continuing introduction .of thefluid under :pressure intoU the .cylinder andl piston oi: smaller fsize, substantiallyfas described,` I

ycombination of a stationarycontact;,and a movable Contact" therefor, said@ parts Vnor- Y mally being in"` engagement with eachother' throughout la limitedf range otmovement ,of i thefmovable contact, together With meansctor initiatingv and continuing movement of the e movable Contact, saidmeans fcomprising a pair of cylinders and Vpistons otdiiierent 4sizes,ineansior initiallyintroducing Aiiuid Vundery pressure into the cylinder"V and piston f rot larger size toinitiatethe movement, means e for arresting movement of thefpistonof large Jsize prior to arrest of movementof .the piston `oismall'size and for thereaftercontinuingin- `troduction 4of the fluidunder lpressure in the cylinderm'of .smaller size to keep thesmovegment throughoutV a Vdesired length of travel,

substantially as described;

combination of a stationary contact,lfafmnv` Vable,` contact rod having" trictional engage- -ment With the stationary contact; throughout Y e aglimited` range of movement,*together with `means for disengaging said v rod `from a said Y contact and" separating 1the parts. a desired distance from eachother, said'means includ- 6." In a Ldevicefoi the class the combinationnot a stationary. Contact, a 'mov-` ment ofthe piston otlar'gesizeprior to Aarrest ment :of thefpiston` oi small size fand `means ,tor thereafter continuing introduction of said f1.0 smaller." size* to v[maintaini the` movement Y throughout the desired distance of travelior size,together Withmeans for introducing gas l Vvunder `pressure intiallylbeneath the piston of-.enlargedv size `for commencing a circuit:

Y `opening operation, themovement oftherod fluid` under `pressure against thepistonfof separation-of fthemovable andrstationary contacts :trom each other, substantially was' i described V combination oi' astationaryA contact, amovable Y contact i rod a having rictional engagement yvvithf .the stationary contact throughout a' limitedrange 4of movement, together with' contact.` and vseparatingtheparts a desiredA distance from each other, said means includeing a'. pair of Vcylinders andr pistons, lof diiierentsiz'es,` means for initially introducing fluid under pressure against the pistonlof larger i .size to ,thereby initiate disengaging movement of the movableicontactirom the stationary contact, means` of arresting" move- 9.0 of movement of the pistonvot small-size and y means f for thereafter continuing introducftionuofviiuid under, pressure against the pisy l.ton of smaller size torltherebyV separatethe movable e and` stationary contacts a desired 9,5' `distance from reach'. other, substantially Vas described. f

`l0;v In .a device ot thefclass described, the

e ,e i i. a combination :of `axstationary` and* movable 17. In a device of theV class described,ithe *contact/s, a cylinder, a piston Working therein "190i and connected tothe movable contact, and

means. :for actuating said pistontormove the Contact for thepurposes otopeningthe cire cuit, said means including a sealed cartridge containingV fluid 'under'` pressure, l said,` car- 195,

Vsioni linlr normally resisting saidV spring Lmeans',.and means torzdivertingcurrent into 1 10 saldiuslblewtension linkunder overload con f -ditions, substantially asdescribed.

llvgfln a'device of the AclassV described, the combination of Vthe stationary and movable Y contacts,'a cylinder and piston-Workingtherei151 u in, saidfpiston connectedto the, movable con-KV tact, together. With meansyfor `:introducing c Y :fluid under pressure into thecylinder toactuf.V J i f Vate the piston under overload conditions, saidl Y i `means, includingja sealed-cartridge having 1,20 compressed; fluid;A therein, .f a lremovable' Wall' section `torsaid cartridgenwhich vvhenre-` moved permits jeXitl of compressediiuid into the cylindertofactuate the pistomandmeans operableunder overloadpconditions or-c'aus- Y i "jingremoval ot said-.yvall section for :thepur-` 'e .posespeciiied,substantially v as described.; i a

V"'12,"Inadevi'ce ofthe-class described, the combination" oiga movable; contact rod adapt` @riformare-initial; waarmee@inizia 9' In ad deVCQ ofthe class described,` the 1 so meansfor disengaging said ,rodi romsaidf" cylinder `means in conjunction therewith,

there being passages `for the introduction of compressed gas for the operation of said pistons, together With means for introducing compressed` gas into said passages to actuate the device under overload conditions, said Ineansincluding a sealed cartridge for the 1 compressed gas, a nipple constituting a porand rupturable when deflected laterally, 1 spring means for causingflateral deflection n scribed.

tion of `the gas inclosure of said cartridge thereof for the purpose of rupturing the de- Vice to release the contained gas, and a fusible tension element for means aforesaid and normally preventing rupture of the device,

constituting a portion of `the circuit under overload conditions, substantially as de` Emo N. NoRDHEM.

restraining the spring said tension means 1 

